Posted
by
ScuttleMonkey
on Monday August 31, 2009 @11:40PM
from the just-try-harder dept.

Hugh Pickens writes "Studies of reproduction in space have previously been carried out with sea urchins, fish, amphibians and birds, but Brandon Keim writes in Wired that Japanese biologists have discovered that although mammalian fertilization may take place normally in space, as mouse embryos develop in microgravity their cells have trouble dividing and maturing. The researchers artificially fertilized mouse eggs with sperm that had been stored inside a three-dimensional clinostat, a machine that mimics weightlessness by rotating objects in such a way that the effects of gravity are spread in every direction. Some embryos were ultimately implanted in female mice and survived to a healthy birth, but at lower numbers than a regular-gravity control group. Part of the difference could be the result of performing tricky procedures on sensitive cells, but the researchers suspect they also reflect the effect of a low-gravity environment on cellular processes that evolved for Earth-specific physics. '"These results suggest for the first time that fertilization can occur normally under G environment in a mammal, but normal preimplantation embryo development might require 1G," concludes the report. "Sustaining life beyond Earth either on space stations or on other planets will require a clear understanding of how the space environment affects key phases of mammalian reproduction."'"

You bet! Even in space, you still need one of these things called a woman to make a baby! Even on earth, we are as a group unable to get our hands on one, just imagine in space where they are a rarity...

"There is no reason to expect that their clinostat successfully captures the essence of the problem"

I looked at the image of that clinostat. The researchers are probably pretty smart people, but there is just no way that a centrifuge on steroids can duplicate zero-G. The embryos have to be subjected for changing gravitational forces. Said forces may cumulatively add up to zero, in theory, but those embryos aren't experiencing theory.

People around here bash scientist a lot, when they are really reading the media. I had a teacher once who had a favorite saying that it seemed like he said at least once a class... "All models are wrong, but some are useful". The same can be said about simulations. After an experiment is performed, in which something is simulated, conclusions are supposed to be drawn. Then, further experiments are supposed to prove or disprove these conclusions. Are you suggesting that they should not have tried this experiment first (which is probably 1/10 of the cost of doing it in space)? They will probably use this experiment as justification for a grant to actually try it in space.

Science is constrained by fiscal realities. And the honest fact is that even if we do have the experiment done completely in space, it is still being done on mice. We won't know how it affects humans until we send a girl up there to get knocked up and see what happens.

There have been all too many jokes about this topic. It is good to see some serious thought and discussion about it.

Since "artificial gravity" is easily created with rotation, conception and pregnancy would have to be within a rotating chamber at least until the embryo develops far enough to tolerate zero-G without adverse effects.

Humans cannot withstand long term micro-gravity. Period. After about a year in space you cannot walk when you land on earth. Our equilibrium depends on gravity too. If we are going to live in space we are going to have to figure out how to create gravity on whatever structure we decide to inhabit. I really doubt we would mutate fast enough to take advantage of weightlessness to survive.

This isn't necessarily a problem. Sure, if you want to walk around Earth then you're going to be in a bit of a fix... But what if you plan on spending the rest of your days in space? What if it's a one-way trip?

If we are going to live in space we are going to have to figure out how to create gravity on whatever structure we decide to inhabit.

I thought we'd already figured this bit out? All you have to do is spin the structure.

I really doubt we would mutate fast enough to take advantage of weightlessness to survive.

We don't need to.

When's the last time you saw somebody sitting out in a snowstorm waiting to mutate and grow an insulating fur coat? Around here we just but on a coat. We're human beings, we have brains, we can make and use tools.

That's the whole point of experiments like this one. We're not going to wait around for environmental forces to craft us into better organisms... We're going to identify the problems and fix them, just like we have for thousands of years. That's what we do.

Humans have survived in space for extended periods without difficulty. Given a large enough breeding population there is absolutely no reason why a space-based species could not evolve. If you have no data, you're just pissing in the wind.

And if you're just making up bullshit that directly contradicts everything we've learned from fifty years of putting people in orbit, you're just an Anonymous Coward.

It would be nice to see some serious data first. The article is based on rotating the cells on the Earth using the stupid assertion that this is somehow the same as no gravity. This is exactly the same as saying that shaking something vigorously is the same as leaving it alone: in both cases the net acceleration is zero. If you try that with a mixture of oil and water the outcome will hardly be the same will it? So why should we expect it to be the same for dividing cells?

You are saying having a G-force spread in all directions is harmful in a way that zero-G wouldn't be. That makes sense for chicken-eggs in gently rotating glass blenders, but not for the embryonic cells within gently rotating chicken-eggs:

Imagine you're at the center of a giant plastic ball full of water. You have to tell whether or not you're in zero-G.
If the ball was sitting on the surface of the earth you might sink or float to the top, and you'd know right away you're not in zero-G.
Now imagine the

But your imaginary "ball" scenario doesn't help show why it should work at all.You experience weightlessness/zero G when you fall without any resistance. If you are in a giant plastic ball full of water and that ball falls, you will definitely still feel like you are falling. Your inner ears will still tell you that you are falling.

If you are in a giant plastic ball full of water and that ball rotates, you may feel like puking after a few spins.

You're right;unfortunately for the analogy our internal "I'm falling" detectors work based on something similar to the uranium-pellet-dropping loophole I mentioned.
In a cell though the molecules don't have finely tuned internal instruments to detect and react to freefall, just like they don't have uranium pellets.

Besides that there are also other problems with the analogy like how some parts of our body can be heavier than others, and water provides little resistance to things as huge as ourselves, so w

Simple: first there is your inner ear balance and second there is the pooling of blood in your head when you are upside down. Both of these are affected differently by freefall and neutral buoyancy on the Earth because the two are very different physical environments.

Yup someone else pointed this out above, you're right it's an "unhelpful" analogy. I tried to clarify what I meant above so I'll drop it here.
What's important is that it's not a problem with it as a zero-G equivalent on the cellular level, it's just a bad analogy.

Not at all - it would know because of the pressure difference across the cell would always be changing direction.

The other guy who responded added this point, but I think he was right that it'd have a negligible effect for embryos, which are tiny.

I haven't looked up info on the device they use but the center of rotation would be quite a way from the cente

Right. Consider some indentical twins. Suppose one twin runs 30km in a loop and end up back where he started while the other twin just sat there waiting for him. In both cases each twin's net displacement, velocity and acceleration are all zero so clearly, biologically, they should both be in the same state right and the twin that ran the 30km should be as well rested as the one that just sat there?

When most people, even most space biologists, talk about "the effect of gravity" they really mean the effect of some force that counters gravity in order to reduce acceleration. ie: in "microgravity" you're still being acted on by gravity, accelerating toward the nearest, largest mass, but that mass is perpetually moving out of the way before you hit it. The forces resisting gravitational acceleration are very small and we say you're in "zero G."

All you need for zero gravitation field (in the Newtonian view) is for the fields to cancel. For example exactly half way between the line joining the centres of two perfact, massive spheres the gravitational field will be zero. Speaking as a physicist I do not see why is this particularly interesting.

Yes, but if you are co-moving with the space station there is no effect in your reference frame--which is what matters in terms of biological processes.

A reference frame in free fall is indistinguishable from one in zero-g(also called the equivalence principle).

So yes, gravity still effects you--that is why you're in an orbit. But it doesn't have the effects it has on you when you are in the non-inertial reference frame that is the surface of the earth (in particular, it doesn't pull your organs towards yo

If you are outside the atmosphere, and not accelerating then you're basically in free fall. Sure, gravity is pulling you somewhere, but it doesn't really have an effect on anything inside the spacecraft (your reference frame is moving with you). I suppose tidal forces and the gravity caused by nearby matter might be detectable, but it's so small as to be ignorable for anything but research on gravity. From a biological perspective there is no discernible effect due to gravity. Given that gravity is prac

If you are outside the atmosphere, and not accelerating then you're basically in free fall.

Err no. If you are in freefall then you ARE accelerating be the very definition of what freefall means. If you let go of a ball it will accelerate downwards and it is in freefall. Freefall means that you are free to fall i.e. that only force acting on you is gravity and so the force of gravity will cause you to accelerate.

Sure, gravity is pulling you somewhere, but it doesn't really have an effect on anything inside the spacecraft (your reference frame is moving with you).

Hang on a minute. How can you possibly say that gravity is pulling you somewhere and at the same time claim that it is not affecting anything inside the spacecraft? What do you think is causing things inside the spacecraft to accelerate then? By definition your reference frame is ALWAYS moving with you even if when your surroundings are not. What gravity does is make this an accelerating reference frame instead of an inertial reference frame and the two are most definitely NOT the same.The equivalence between gravity and acceleration is one of the core concepts of GR.

From a biological perspective there is no discernible effect due to gravity.

Yes there is. The reason that your organism is accelerating towards the centre of the planet is an easily measurable effect. In both the case of freefall and sitting on the surface of the planet there are discernable effects due to gravity. In the first case you are accelerating and in the second case you are not accelerating because there is a reaction force between you and the surface of the planet equal and opposite to your weight. In the latter case your internal structure must transmit this normal force throughout your body to cancel your weight in order to prevent all parts of you from accelerating but in both cases the force of gravity acts on all parts of you to the same degree (assuming the same field strength).

This is the same as taking a lift. When the lift accelerates down it does not mean that gravity has suddenly become less it just means that your body has a reduced normal force to distribute because you have a small, downwards acceleration.

If you are outside the atmosphere, and not accelerating then you're basically in free fall.

Err no. If you are in freefall then you ARE accelerating be the very definition of what freefall means. If you let go of a ball it will accelerate downwards and it is in freefall. Freefall means that you are free to fall i.e. that only force acting on you is gravity and so the force of gravity will cause you to accelerate.

Sure, gravity is pulling you somewhere, but it doesn't really have an effect on anything inside the spacecraft (your reference frame is moving with you).

Hang on a minute. How can you possibly say that gravity is pulling you somewhere and at the same time claim that it is not affecting anything inside the spacecraft?

Orbit is just freefall around an object due to gravity. Yes, gravity acts on everything in the spacecraft, but not _relative_ to the spacecraft. Maybe English is not your primary language?

As soon as you are in free fall, you're not affected by gravity (at least not in a significant way).

Then could you please explain why you are accelerating downwards? Hint: it is due to a force called GRAVITY. Freefall is when the ONLY force that acts on you is gravity. Under normal circumstances there are two forces which act on you: gravity and a reaction force between you and whatever you are sitting, standing, lying etc. on. In freefall you remove this normal force NOT gravity.

Using acceleration to counteract undesirable effects of microgravity appears to be a universally ignored solution. It's like people are so amazed by how awesome zero-g is that they can't accept that working against it might be the best option.

problem: humans lose bone mass in zero-gbrain dead solution: we need to change humans with drugs! oh, and we'll make them exercise more too.problem: embryos don't develop normally in zero-gbrain dead solution: we need to study embryonic development more, and hey, maybe we can find some drugs to fix it!problem: transferring cryogenic propellant in zero-g is hardbrain dead solution: we need to learn more about fluid dynamics in zero-g!

Back in the Gemini days they actually bothered to join a pair of spacecraft together and spin them up. The effect was about 1000th of a g, but it was a successful mission. Everyone presumed that NASA would continue this research after Apollo, with longer tethers and slower rotation, a 1g environment could be created. That didn't happen. Instead, the fixed module concept took over and "studying the effects of zero-g" became the mantra. No matter, the Japanese space program proposed a module that would allow the study of incremental gravity on mammals, everything from low gravity to three times earth gravity, or the astronauts could sleep in it. That was scrubbed.

Well, one advantage to using drugs is, in theory, if we have issues on the Moon or Mars, we merely have to adjust the dosage. It'll be tough to build a 1G chamber on the Moon. Also, the research into this problem has helped people with osteoporosis here on Earth.

That said, I tend to agree with you. Astronauts spend two-and-a-half hours per day exercising so that they don't collapse when they get back to Earth. At this risk of sounding like a cruel taskmaster, that's time that could be spent doing experiments and the other things that our tax dollars are paying for.

The worst part is that there doesn't even appear to be any research going on in this area. How much gravity is necessary? 0.5G? 0.3G? 0.1G? Could they work in 0.3G and sleep in 0G? Could they work in 0G and sleep in 0.3G? This could affect the design of long-duration spacecraft.

While the research into drugs is a good thing and helps us down here on Earth, to me it is not necessarily a good solution because you have to pack enough drugs to get them to Mars, enough drugs for them while on Mars, and enough drugs to get them back to Earth.

It's like people are so amazed by how awesome zero-g is that they can't accept that working against it might be the best option.

That's probably what influences the designers of spacecraft.. the awesomeness of zero-g...

Either that or because systems involving artificial gravity are too costly to justify themselves, and the "brain dead" solutions are actually smart solutions which save money/make missions possible.
Perhaps a spaceflight engineer would respond "problem: no gravity in orbit, we're not used to this. brain dead solution: create artificial gravity! price/practicality is no object if it means we have no new problems to solve!"

Maybe at some point there will be a zero-g problem which really is easier to solve with centrifuges than with anything else, and you can bet when that point comes centrifuges will be chosen.

No matter, the Japanese space program proposed a module that would allow the study of incremental gravity on mammals, everything from low gravity to three times earth gravity, or the astronauts could sleep in it. That was scrubbed.

Why (not) on Earth would you want to simulate >1g in space? Anything below 1g, sure, but for greater you could just use a centrifuge on Earth where it doesn't take 1000kg of propellant to get every kilogram of payload to your test apparatus.

Using acceleration to counteract undesirable effects of microgravity appears to be a universally ignored solution.

It's not ignored - it's turned out to be devilishly difficult to arrange.

Back in the Gemini days they actually bothered to join a pair of spacecraft together and spin them up. The effect was about 1000th of a g, but it was a successful mission. Everyone presumed that NASA would continue this research after Apollo, with longer tethers and slower rotation, a 1g environment could be created.

Everyone who? Because everyone I know is familiar with the problems with those tethers bring with them.

Its extraordinarily difficult to stop and start the rotation. Its difficult to avoid tension problems during payout, it's REALLY difficult to prevent snarls during retraction. It's extraordinarily incredibly difficult to make orbital corrections while tethered and spinning...

Until someone comes up with some engineering solutions to test (and they are working on them and two tether deployment tests (both failures) have flown on the Shuttle), any experimentation is moot - kinda like sticking your finger into boiling water to see if it burns you.

Using acceleration to counteract undesirable effects of microgravity appears to be a universally ignored solution. It's like people are so amazed by how awesome zero-g is that they can't accept that working against it might be the best option.

Even considered that it's not as easy as it sounds? One of the main problems (I'm sure there's more) is that unless your "vehicle" is huge, then making it spin causes both a "gravity gradient (gravity on your head will be smaller than on your feet) and strong Coriolis forces (people and objects cannot follow a straight line).

I am not suggesting that your point is without merit or that the best solution to long space deployments might not be to create artificial gravity as as you correctly point out it could kill a whole flock of birds with one stone but there are other considerations.

Physicists still don't entirely understand the force of gravity. It might be that simulating the macro effects of it with acceleration does not solve some problems on the micro and smaller scales.

In his Known Space universe, the true separation of space-based ("Belter") culture from Earth-based ("Flatlander") culture occurred when the Belters completed their massive 'terraforming' of the inside of an asteroid named Sanctuary as a shelter and home for pregnant Belter women. Rotating the asteroid up to 1-g, they eliminated their last unwanted ties to Earth as women no longer needed to return to the home planet for the period of gestation and birth.

Though, if I remember correctly, Larry Niven's justification for the need was a bit different, as he reasoned that a human fetus brought to term in very low gravity would grow to a size that endangered the life of the mother... I think.

They carried out reproduction in space of sea urchins, fish, amphibians and birds, but no mice? If I were to study the effects of microgravity on pregnancy, I would put something similar to humans (at least a mammal) at the top of my list, instead of first trying a whole list of species that don't really resemble us.
Why use centifuges to "simulate" zero G (?!) and not just send a few mice up to the ISS? OK, it might be difficult to get them to actually reproduce, maybe put them on a 1G centrifuge for the actual copulation bit and then let them float again.

Thank you for your interest in our Copulation in Space Program! After reviewing your qualifications, we have determined that you unfortunately do not qualify. At this time, we are only seeking experienced candidates for the mission, and seeing as how you have ZERO experience with sexual reproduction, we are unable to process your application. We will keep your application on file and, should an appropriate opportunity arise, we'll contact you in your mother's basement at that time.

I think this is going to be a minor concern in the grand scheme of "sustaining life on space stations and other planets".

And if this problem multiplies with successive generations? How big a problem would it be if zero-g environments reduced the rate of fecundity by 10% for every generation? That 1000 year mission to a life sustaining planet suddenly gets cut short because the population is bring halved every 50 years.
What other "obvious" problems should we not worry about when dealing with long term spaceflight?